
Fast Ethernet Controller (FEC)
19-28
Freescale Semiconductor
NOTE
When the software driver sets an E bit in one or more receive descriptors,
the driver should follow with a write to RDAR.
19.5.1.3
Ethernet Transmit Buffer Descriptor (TxBD)
Data is presented to the FEC for transmission by arranging it in buffers referenced by the channel’s TxBDs.
The Ethernet controller confirms transmission by clearing the ready bit (TxBD[R]) when DMA of the
buffer is complete. In the TxBD, the user initializes the R, W, L, and TC bits and the length (in bytes) in
the first longword and the buffer pointer in the second longword.
The FEC clears the R bit when the buffer is transferred. Status bits for the buffer/frame are not included in
the transmit buffer descriptors. Transmit frame status is indicated via individual interrupt bits (error
conditions) and in statistic counters in the MIB block. See
Section 19.4.1, “MIB Block Counters Memory
for more details.
0
6
MC
Set if the DA is multicast and not BC.
0
5
LG
Rx frame length violation. Written by the FEC. A frame length greater than RCR[MAX_FL] was
recognized. This bit is valid only if the L-bit is set. The receive data is not altered in any way unless
the length exceeds 2047 bytes.
0
4
NO
Receive non-octet aligned frame. Written by the FEC. A frame that contained a number of bits not
divisible by 8 was received, and the CRC check that occurred at the preceding byte boundary
generated an error. This bit is valid only if the L-bit is set. If this bit is set, the CR bit is not set.
0
3
Reserved, must be cleared.
0
2
CR
Receive CRC error. Written by the FEC. This frame contains a CRC error and is an integral number
of octets in length. This bit is valid only if the L-bit is set.
0
1
OV
Overrun. Written by the FEC. A receive FIFO overrun occurred during frame reception. If this bit is
set, the other status bits, M, LG, NO, CR, and CL lose their normal meaning and are zero. This bit
is valid only if the L-bit is set.
0
0
TR
Set if the receive frame is truncated (frame length > 2047 bytes). If the TR bit is set, the frame must
be discarded and the other error bits must be ignored as they may be incorrect.
2
15–0
Data
Length
Data length. Written by the FEC. Data length is the number of octets written by the FEC into this
BD’s data buffer if L equals 0 (the value is equal to EMRBR), or the length of the frame including
CRC if L is set. It is written by the FEC once as the BD is closed.
4
15–0
A[31:16]
RX data buffer pointer, bits [31:16]
1
6
15–0
A[15:0]
RX data buffer pointer, bits [15:0]
1
The receive buffer pointer, containing the address of the associated data buffer, must always be evenly divisible by 16. The
buffer must reside in memory external to the FEC. The Ethernet controller never modifies this value.
Table 19-29. Receive Buffer Descriptor Field Definitions (continued)
Word
Field
Description
MCF5329 Reference Manual, Rev 3
Содержание MCF5329
Страница 106: ...ColdFire Core 3 32 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 126: ...Enhanced Multiply Accumulate Unit EMAC 4 20 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 148: ...Cache 5 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 154: ...Static RAM SRAM 6 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 184: ...Power Management 8 18 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 204: ...Reset Controller Module 10 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 220: ...System Control Module SCM 11 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 228: ...Crossbar Switch XBS 12 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 268: ...General Purpose I O Module 13 40 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 392: ...SDRAM Controller SDRAMC 18 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 436: ...Fast Ethernet Controller FEC 19 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 564: ...Liquid Crystal Display Controller LCDC 22 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 594: ...FlexCAN 23 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 678: ...Pulse Width Modulation PWM Module 26 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 684: ...Watchdog Timer Module 27 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 692: ...Programmable Interrupt Timers PIT0 PIT3 28 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 704: ...DMA Timers DTIM0 DTIM3 29 12 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 720: ...Queued Serial Peripheral Interface QSPI 30 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 754: ...UART Modules 31 34 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 770: ...I2 C Interface 32 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 790: ...Message Digest Hardware Accelerator MDHA 33 20 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 866: ...Debug Module 36 50 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 902: ...Register Memory Map Quick Reference A 26 Freescale Semiconductor MCF5329 Reference Manual Rev 3...